Design, synthesis and biological evaluation of novel steroidal spiro-oxindoles as potent antiproliferative agents

Two series of novel steroidal spiro-pyrrolidinyl oxindoles 3a-t and 6a-c were designed and synthesized from dehydroepiandrosterone using the 1,3-dipolar cycloaddition as the key step and further evaluated for their antiproliferative activities for four human cancer cell lines (MGC-803, EC109, SMMC-7721 and MCF-7). This protocol achieved the formation of two CC bonds, one CN bond and the creation of one new five-membered pyrrolidine ring and three contiguous stereocenters in a single operation. Biological evaluation showed that these synthesized steroidal spiro-pyrrolidinyl oxindoles possessed moderate to good antiproliferative activities against the tested cell lines and some of them were more potent than 5-Fu. Particularly, compound 3g showed good antiproliferative activity against SMMC-7721 (IC50=0.71μM). Steroid dimer 6b showed improved antiproliferative activities against SMMC-7721 and MCF-7 with the IC50 values of 4.30 and 2.06μM, respectively. Flow cytometry analysis demonstrated that compound 3n caused the cellular early apoptosis and cell cycle arrest at G2/M phase in a concentration- and time-dependent manner. [Corrected]